A user interface is the method by which a human and a computer system exchange information and
instructions.

You may like some programs and dislike others. When you decide whether or not a program is useful you will probably
be considering :

Whether the program will do the jobs you want it to.

How easy it is to use the program.

It is the job of a user interface to make a program easy to use. Today the user interface is regarded as being so
important that up to 90% of a computer program may be devoted to managing it. Software designers use many tools
and techniques to help make an interface easy to use. These include :

Colour to highlight.

Sound for warning messages.

Flashing symbols.

Careful design of screen layouts.

Keeping the interface consistent on all of the screens of the program.

Each type of interface has its own advantages and disadvantages. Often the type of user interface that is used on a
computer system is determined by the operating system. For example most programs that run on computers using a
Microsoft Windows operating system have a graphical user interface.

1. Window : An area of the screen which is used to display a particular program or piece of work. Many windows can
be displayed on the screen at the same time. e.g.

2. Icon : An informative picture / symbol displayed on the screen which the user chooses to select an action. Icons can
usually be used to represent software packages, documents and hardware devices. e.g.

3. Menu : A list of options which the user can pick from. Menus can be pull-down (selected from a menu bar at the top
of the screen) or pop-up (selected by pressing a mouse button). e.g.

4. Pointer : A symbol such as an arrow which is moved by a pointing device and can be used to select objects.

WIMP user interfaces are now very popular and are used on most computers. Examples of operating systems/programs
that have a WIMP Interface are :

Windows

Risc-Os

Any piece of software running under one of the above operating systems.

When you use a program such as a word processor that has a WIMP interface it is often the case that the document you
are creating looks exactly the same on the screen as it will when it is printed out. If this is the case then the program is
described as being WYSIWYG. This stands for What You See Is What You Get.

Advantages

Disadvantages

Most operations are self-explanatory so that you do
not have to remember lots of commands.

Some operations are much easier using a GUI with a
pointer. e.g. selecting text or drawing pictures.

Often you can have more than one program running
at the same time, each of them using different
windows.

Often GUIs are WYSIWYG. What you see on the
screen is what you get if you do a printout.

Often with a GUI many programs use a similar
interface, so it is easier to learn how to use a new
program.

Most GUIs provide good help facilities.

GUIs can take up a lot of memory and need to be
run on a fast computer. If you have a slow
computer, a GUI may work slowly or not at all.

When you are designing an information system you will need to design the user interface. It is likely that because you are
using an application package you will have to design your interface to fit in with the facilities the package offers you.

You should try sketching the layout of the screens that you will include in your system before you set the system up.
Remember to bear in mind the guidelines (e.g. using simple language) given at the top of the page to help you.

For some applications a special purpose user interface is required. These are applications for which a
standard user interface on an ordinary computer is not suitable. Here are two applications for which this is the
case :

Flying an Aircraft : Pilots use computers to fly aeroplanes. But a pilot does not fly an aeroplane using a mouse
and a monitor. The pilot would not be able to control the plane quickly enough to prevent a crash with a mouse
and there is not enough space on a monitor to give the pilot all the information he needs. Instead specialised input
devices such as a yolk, pedals and many banks of switches and levers are input devices. Output devices such as
computer monitors, dials and warning buzzers are used to pass information to the pilot.

Bank Cash Machine : People who use a cash machine do not want to have to learn how to use a computer to
get money. So a very simple menu-driven interface which uses a small keypad and card slot as input devices is
employed. Output is provided by a monitor, a small printer and the hole that the money comes out of!

A special purpose user interface consists of not only software but also all of the input devices and output devices used to
enable communication between the user and the computer.